The FDA has approved a new dosing regimen for Biogen and Eisai’s Leqembi (lecanemab-irmb), introducing once-every-four-weeks intravenous (IV) maintenance dosing for patients with early Alzheimer’s disease.
Patients can transition to the monthly dose after completing 18 months of biweekly infusions. The new dosing regimen aims to maintain the therapy’s benefits while improving convenience for patients and caregivers.
The treatment is somewhat time-intensive, with a one-hour intravenous infusion every two weeks and regular MRI scans.
Medication adherence is a significant challenge for cognitively impaired individuals. A study in PLOS One reported non-adherence rates ranging from 10.7% to 38%, influenced by the severity of cognitive impairment and the complexity of medication regimens. Simplified dosing schedules could help address the issue.
Leqembi was first approved in 2023 as a monoclonal antibody targeting amyloid-beta protofibrils and plaques — proteins that cause brain cell damage and cognitive decline in Alzheimer’s disease. By continuously clearing these harmful substances, Leqembi has been shown to slow disease progression and preserve cognitive abilities. Its label carries a boxed warning for amyloid-related imaging abnormalities (ARIA), which can cause brain swelling or small bleeds in the brain.
The updated dosing regimen builds on insights from the Clarity AD Phase III study. Data from trial showed that after 18 months of biweekly treatment, lecanemab reduced cognitive decline by 0.45 points on the Clinical Dementia Rating-Sum of Boxes (CDR-SB) scale compared to placebo. Over three years, the therapy further reduced decline by 0.95 points relative to a matched natural history cohort.
The CDR-SB scale measures memory, problem-solving and daily functioning. A 0.5 to 1-point improvement on the scale can mean the difference between mild impairment and the loss of independence.
Patients treated with lecanemab maintained their ability to engage in hobbies, complete household tasks and participate in social activities, significantly enhancing their quality of life.
Studies also highlight the importance of continuous treatment. In the Phase II Study 201, a gap in therapy led to the re-accumulation of amyloid plaques and a return to placebo-level rates of cognitive decline. Monthly dosing could ensure adherence, maximizing sustained benefits.
Leqembi is approved in the US, Japan and the UK, with applications pending in 17 additional regions.
Developers Eisai and Biogen are also pursuing FDA approval for a subcutaneous autoinjector for weekly maintenance dosing. Analysts believe if approved, it could expand patient access to intravenous treatment by increasing center capacity.
Efforts to improve dosing efficiency extend beyond Leqembi. Eli Lilly’s donanemab (Kisunla) has shown that a gradual titration approach can reduce the risk of amyloid-related imaging abnormalities by nearly half while maintaining efficacy.
Securing insurance coverage has been a challenge for Eisai and Biogen. Medicare covers the drug, but it requires patients and clinicians to participate in a registry that collects treatment data.
Sales of Leqembi were off to a slow start because of some of these challenges but steadily increased. Biogen reported $67 million in global in-market sales for the treatment in the third quarter of 2024, with $39 million from the US.
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